best bet for long distance wireless

Hi All

I currently have a wndr3400  dual band (2.4 Ghz ssid and 5 ghz ssid) router connected to a cable modem for my wireless in my house.  I live on a 5 acre lot with a mother in law quarters some distance from the main house.  I have looked at the wn2000rpt range extender to supply wireless in the mother in law quarters but noticed that it will only extend the 2.4 Ghz band and not the 5Ghz I would like both bands the 5 Ghz for the movie streaming.  Is is possible to install another wndr 3400 wireless router behind the current one that I have in my house so I will have both bands in the mother in law quarters?  Or does anyone have a better way to solve this.  I am not real smart in this area of modems and routers so any help would be appreciated.

Thanks